CN103896305A

CN103896305A - Method for improving specific surface area of SAPO-34 molecular sieve

Info

Publication number: CN103896305A
Application number: CN201310743180.8A
Authority: CN
Inventors: 常云峰; 丁月
Original assignee: TIANJIN SIGMA INNOVA TECHNOLOGY Co Ltd
Current assignee: TIANJIN SIGMA INNOVA TECHNOLOGY Co Ltd
Priority date: 2013-12-24
Filing date: 2013-12-24
Publication date: 2014-07-02

Abstract

The invention relates to a method for improving the specific surface area of an SAPO-34 molecular sieve. The method comprises the steps of preparing a 0.07-0.08% acid solution, adding the SAPO-34 molecular sieve, stirring in a thermostat water bath at a certain temperature, filtering and washing the exchanged product, drying the product in an oven at 110 DEG C for 2 hours, and roasting the dried product in a muffle furnace at 55 DEG C for 2 hours to obtain a modified SAPO-34 molecular sieve, wherein the mass ratio of the SAPO-34 solid product to the acid solution is 1:(40-60). The method is characterized in that compared with the product before modification, the specific surface area and total pore volume of the modified SAPO-34 molecular sieve are improved, the morphology of the modified SAPO-34 molecular sieve is not obviously changed, and the diolefin selectivity in methanol to olefin (MTO) reaction is improved.

Description

A kind of method that improves SAPO-34 molecular sieve specific surface area

Technical field

The invention belongs to molecular sieve field, relate to the method for modifying of SAPO-34 molecular sieve, be specifically related to a kind of method of the SAPO-34 of raising molecular sieve specific surface area.

Background technology

The emphasis of the technological process research of methanol-to-olefins (MTO) is aspect screening of catalyst and technology of preparing.In exploration converting methanol to prepare low carbon olefin catalyzer process, people attempted various molecular sieves, from early stage Si-Al zeolite silicoaluminophosphamolecular molecular sieves SAPO-34 till now.It is high that SAPO-34 molecular sieve has methanol conversion as the catalyzer of MTO reaction, ethene, the advantage that Propylene Selectivity is higher, but the SAPO-34 sometimes newly preparing is difficult to excavate its excellent properties in MTO reaction without any modifying process.Therefore people are doing many research aspect the modification of SAPO-34 molecular sieve.

The application carries out modification for the SAPO-34 molecular sieve having synthesized by chemical treatment method, wishes on the basis of not destroying SAPO-34 original structure, to improve its specific surface area, thereby reaches the advantage of further raising diene selective.

Summary of the invention

The object of the present invention is to provide a kind of method of the SAPO-34 of raising molecular sieve specific surface area, improve through present method molecular sieve specific surface area after treatment, total pore volume improves, and considerable change does not occur pattern, and in MTO reaction, diolefin selective improves.

It is as follows that the present invention realizes object technical scheme:

A method that improves SAPO-34 molecular sieve specific surface area, step is as follows

Compound concentration is 0.07%～0.08% acidic solution, add SAPO-34 molecular sieve, in certain temperature thermostat water bath, stir suitable, product after exchange finishes carries out filtration washing, product is put in 110 DEG C of baking ovens and is dried 2 hours, by the roasting 2 hours in 550 DEG C of retort furnaces of dried product, obtain the SAPO-34 molecular sieve after modification again, described SAPO-34 solid product and the mass ratio of acidic solution are 1:40～60.

And described acidic solution is organic multicomponent acid, preferably oxalic acid.

And described water bath with thermostatic control temperature is 15～85 DEG C.

And described stirring appropriate time is 20～300 minutes.

Advantage of the present invention and positively effect are as follows:

Feature of the present invention is that SAPO-34 molecular sieve after modification is compared with product before modification, and specific surface area improves, and total pore volume improves, and considerable change does not occur pattern, and in MTO reaction, diolefin selective improves.

The present invention's SAPO-34 product after treatment before specific surface area improves, and total pore volume improves, and considerable change does not occur pattern, and in MTO reaction, diolefin selective improves.

Brief description of the drawings

Fig. 1: be the scanning electron microscope (SEM) photograph of SAPO-34-a;

Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 are the scanning electron microscope (SEM) photographs of embodiment 1-4 and counter-example 1.

Fig. 7 is the MTO diolefin selective comparison diagram of embodiment 1,2.

Embodiment

Below in conjunction with embodiment, the present invention is further described, and following embodiment is illustrative, is not determinate, can not limit protection scope of the present invention with following embodiment.

Embodiment 1

A method that improves SAPO-34 molecular sieve specific surface area, step is as follows:

First 200 grams of the oxalic acid solutions that compound concentration is 0.074%, be poured in there-necked flask, put into again 4 grams of SAPO-34(after roasting and be numbered SAPO-34-a), transfer them in thermostat water bath, arrange 25 DEG C and stir 80 minutes, the product that exchange finishes carries out after filtration washing, be put in 110 DEG C of baking ovens and dry 2 hours, by the roasting 2 hours in 550 DEG C of retort furnaces of dried product, obtain the product after modification again, numbering SAPO-34-b.

Embodiment 2

First 200 grams of the oxalic acid solutions that compound concentration is 0.074%, be poured in there-necked flask, put into again 4 grams of SAPO-34(after roasting and be numbered SAPO-34-a), transfer them in thermostat water bath, arrange 50 DEG C and stir 80 minutes, the product that exchange finishes carries out after filtration washing, be put in 110 DEG C of baking ovens and dry 2 hours, by the roasting 2 hours in 550 DEG C of retort furnaces of dried product, obtain the product after modification again, numbering SAPO-34-c.

Embodiment 3

First 200 grams of the oxalic acid solutions that compound concentration is 0.074%, be poured in there-necked flask, put into again 3 grams of SAPO-34(after roasting and be numbered SAPO-34-a), transfer them in thermostat water bath, arrange 75 DEG C and stir 80 minutes, the product that exchange finishes carries out after filtration washing, be put in 110 DEG C of baking ovens and dry 2 hours, by the roasting 2 hours in 550 DEG C of retort furnaces of dried product, obtain the product after modification again, numbering SAPO-34-d.

Embodiment 4

First 200 grams of the oxalic acid solutions that compound concentration is 0.074%, be poured in there-necked flask, put into again 4 grams of SAPO-34(after roasting and be numbered SAPO-34-a), transfer them in thermostat water bath, arrange 50 DEG C and stir 140 minutes, the product that exchange finishes carries out after filtration washing, is put in 110 DEG C of baking ovens and dries 2 hours, by the roasting 2 hours in 550 DEG C of retort furnaces of dried product, obtain the product S APO-34-e after modification again.

Counter-example 1

First 200 grams of the oxalic acid solutions that compound concentration is 0.127%, be poured in there-necked flask, put into again 3 grams of SAPO-34(after roasting and be numbered SAPO-34-a), transfer them in thermostat water bath, arrange 75 DEG C and stir 80 minutes, the product that exchange finishes carries out after filtration washing, is put in 110 DEG C of baking ovens and dries 2 hours, by the roasting 2 hours in 550 DEG C of retort furnaces of dried product, obtain the product S APO-34-f after modification again.

Table 1 is specific surface area and the pore volume data of embodiment and counter-example

Table 2 is MTO diolefin selective correlation datas of embodiment 1,2

Testing of materials method

The crystal morphology of target product is undertaken by the electron microscope TM-1000 of Hitachi, Ltd, and sample is not gold-plated, and then coated with conductive adhesive tape on specimen holder selects different regions to observe and imaging.

The specific surface area of target product is measured by the Gemini2360 of Merck & Co., Inc, before sample measurement, need to carry out degassed pre-treatment, use the degassed station of MicromeriticsV60 sweeping type degassed, degasification process is divided two stages: i.e. the nitrogen purging 30 minutes of 30 ml/min under room temperature condition; Then be warming up to after 350 DEG C the nitrogen purging of 30 ml/min 2 hours.

The catalytic effect evaluation of target product is carried out in fixed bed reaction apparatus, and experiment condition is: molecular sieve loadings is 0.5 gram, 420 DEG C of temperature of reaction, and methanol content is 95%, air speed is 20h-1.The gas chromatograph GC5890 that reaction product is used hewlette-packard to produce separates, condition determination: flame ionization ditector, and 20 DEG C/min rise to 160 DEG C, and external standard method is quantitative.

Claims

1. a method that improves SAPO-34 molecular sieve specific surface area, is characterized in that: step is as follows

Compound concentration is 0.07%～0.08% acidic solution, add SAPO-34 molecular sieve, in certain temperature thermostat water bath, stir suitable, product after processing finishes carries out filtration washing, product is put in 110 DEG C of baking ovens and is dried 2 hours, by the roasting 2 hours in 550 DEG C of retort furnaces of dried product, obtain the SAPO-34 molecular sieve after modification again, described SAPO-34 solid product and the mass ratio of acidic solution are 1:40～60.

2. the method for raising SAPO-34 molecular sieve specific surface area according to claim 1, is characterized in that: described acidic solution is organic multicomponent acid.

3. the method for raising SAPO-34 molecular sieve specific surface area according to claim 1, is characterized in that: described acidic solution is oxalic acid.

4. the method for raising SAPO-34 molecular sieve specific surface area according to claim 1, is characterized in that: described water bath with thermostatic control temperature is 15～85 DEG C.

5. the method for raising SAPO-34 molecular sieve specific surface area according to claim 1, is characterized in that: described stirring appropriate time is 20～300 minutes.